1. Field of the Invention
The present invention relates to a semiconductor device manufacture. More particularly, the present invention relates to a method of manufacturing a semiconductor device for inhibiting the corrosion of a copper (Cu) layer after chemical mechanical polishing (CMP) and chemical mechanical polishing equipment used in the same.
2. Description of the Related Art
As high integration and high performance of semiconductor devices continue to make progress, the use of a Cu layer as a wiring material in a semiconductor device has been proposed. A Cu layer is patterned by a damascene technique to obtain wiring lines. The patterning of a Cu layer involves the use of CMP process after forming the Cu layer.
A Cu layer, however, is susceptible to corrosion during its formation. A Cu layer can be corroded during a CMP process or during a cleaning process after the CMP process. It is well known that the corrosion of a Cu layer results from galvanic corrosion and photo assisted corrosion. One approach to inhibiting the corrosion of a Cu layer during CMP includes continuously forming a corrosion barrier layer on the surface of a metal layer during CMP.
However, the corrosion of a Cu layer may occur during a post CMP process. More specifically, wafers to be loaded into CMP equipment for CMP of a Cu layer are held in a carrier, and several wafers are loaded into the CMP equipment at one time. Thus, wafers on which CMP is performed are among wafers loaded into the CMP equipment that must stand-by at an unloading station of the CMP equipment until the remaining wafers are subjected to CMP. For example, if twenty-five wafers corresponding to one run are loaded into the CMP equipment, wafers initially subjected to CMP may wait for about more than two hours at the unloading station.
The surfaces of the wafers being on stand-by are wet from a solution used in CMP, and a material that induces corrosion such as a slurry or an oxidizer may remain in the solution. The solution, wetting the polished surface of a Cu layer, may lead to galvanic corrosion or photo assisted corrosion. If two or more hours are required as a stand-by time as described above, the significant corrosion may occur. Furthermore, since the polished wafers collect at the stand-by station and are then transferred to a cleaning step, the corrosion may continuously occur during a transfer time along with the stand-by time.
To solve the above problems, it is a feature of an embodiment of the present invention to provide a method of manufacturing a semiconductor device which can prevent the polished surface of a Cu layer from being corroded after chemical mechanical polishing (CMP).
It is another feature of an embodiment of the present invention to provide CMP equipment for protecting the polished surface of a Cu layer from corrosion after CMP.
Accordingly, to provide the above features, the present invention provides a method of manufacturing a semiconductor device for preventing the corrosion of a Cu layer. When a wafer, on which a Cu layer is formed, stands by so as to be transferred to a cleaning system after being subjected to CMP in a CMP equipment, a solution containing a corrosion inhibitor is provided to the wafers collected at a stand-by station, so as to keep at least the polished surface of the Cu layer wet with the solution. Then, the wafers collected at the stand-by station are transferred to the cleaning system and cleaned. In this case, the solution is a solution in which the corrosion inhibitor is added to de-ionized water. Benzo-tri-azole is preferably used as the corrosion inhibitor. While transferring the wafer to the cleaning system, the surfaces of the transferred wafers are kept wet with the solution containing the corrosion inhibitor.
An embodiment of the present invention also provides CMP equipment including a polishing station including a polishing pad on which wafers from a carrier are sequentially loaded and a Cu layer formed on each wafer is polished, and a stand-by station where a vacant carrier, into which wafers unloaded by a robot at the polishing station are sequentially inserted, stands by and for supplying a solution containing a corrosion inhibitor onto the polished surface of the Cu layer on the inserted wafers.
In this case, the stand-by station includes a solution vessel for containing the solution so that the carrier may be loaded and soaked in the supplied solution, a supply pipe for supplying the solution to the solution vessel, a discharge pipe for drawing the solution from the solution vessel, and a solution supply container, connected to the supply pipe, for supplying the solution.
The present invention makes it possible to protect the polished Cu layer on a wafer from post CMP corrosion.
These and other features of the present invention will be readily apparent to those of ordinary skill in the art upon review of the detailed description that follows.